Look through the front deck vent & you should see it, access is another issue depending on which version you have. I have one here that we are using this summer awaiting restoration & will be dissecting & re-engineering the whole under-deck storage compartment. Also, I have found about 50% of non-functioning horns are from bad horn switches, so before you dig into this make sure your switch is passing current to the horn.

I have seen a few "interesting" things with boats out of the WESMAR plant, I put them in the front vent duct so the sound exited the front vent opening to comply with USCG. The good news is yours is clicking, follow the clicking & you will find the horn.